The invention relates to apparatus for optically exposing documents for copying. More particularly, it relates to an exposure system for automatically copying either one or both sides of a sheet document.
A typical prior art device is illustrated by Kelly U.S. Pat. No. 3,844,653 in which a scanner is shown that has a simplex scanning station and a duplex scanning station. Document side reversal is by a rotating drum in which the first exposed side is positioned next to the drum surface thus placing on the outside of the drum the unexposed side for exposure. Knechtel U.S. Pat. No. 4,110,030 discloses a document inverter in which transport rolls position and move a document behind an exposure window exposing one side of the document. A control device is provided for reversing the rotation of the transport roll pairs before the original leaves the roll pair adjacent the exit and, as a result, the roll after reversal of the rotation thereof transports the original document again past the exposure window only this time the back, or other, side of the document is exposed.